Lipoic acid in animal models and clinical use in diabetic retinopathy

Oxidative stress, a consequence of excessive production of reactive oxygen species (ROS), is a factor in the development of many diseases, including diabetes and its complications. Alpha-lipoic acid (ALA), a natural thiol antioxidant, has been shown to have beneficial effects on oxidative stress parameters in various tissues. This article is an up-to-date review of current thinking regarding ALA and its use in providing antioxidant (AO) drug therapy for ocular dysfunction due to diabetic retinopathy (DR).

ALA prevents micro- and macro-vascular damage through normalized pathways downstream of mitochondrial overproduction of ROS, and preserves pericyte coverage of retinal capillaries. In addition, clinical studies suggest that oral administration of ALA can improve insulin sensitivity in patients with type-2 diabetes. Moreover, ALA treatment has been shown to suppress expression of vascular endothelial growth factor (VEGF), angiopoietin 2 and erythropoietin via blockade of superoxide formation.

The diverse beneficial effects of ALA, many of which have only recently been uncovered, suggest that it acts by multiple mechanisms on oxidative stress parameters. Consequently, ALA supplementation is an achievable adjunct therapy to help prevent vision loss in diabetic patients. Finally, further research to better understand the mechanism of ALA will be useful for the development of more effective therapies in patients affected by DR.